The present invention relates generally to the art of highway safety barriers and methods of installing same. More particularly, the present invention relates to cable barrier systems used along edges and in the medians between roadways and the like, and methods of erecting such barriers.
As the number of vehicles has increased on the roadways, so too has the risk of accidents. Consequently, concern over vehicle safety, as well as the safety of vehicle passengers and roadway workers, has also increased. As one means of protection, attempts have previously been made to erect safety barriers along the roadways and between medians of highways. These barriers help to prevent errant vehicles from leaving the roadway and/or crossing lanes into oncoming traffic, thus causing significant damage and/or injury to the property of others.
Early efforts in constructing such barriers consisted of erecting rows of concrete posts anchored to the ground adjacent the roadways. Eventually, this gave way to the erection of more continuous permanent concrete structures, and in cases where more temporary protection is required (e.g., roadway construction), the use of larger pre-cast concrete barriers that may be placed in position and reused as needed has become increasingly popular. While these more permanent massive concrete barriers are helpful in preventing vehicles from entering oncoming traffic lanes, they do not prevent vehicles from rebounding back into the original lane of traffic, and have been known to frequently cause more accidents in this manner.
Less permanent breakaway cable barrier systems are now available which help prevent out-of-control vehicles from entering oncoming traffic or rebounding into the original traffic lane. Such breakaway barrier systems have gained substantial popularity in recent years and are typically composed of a series of steel line-post cabling structures anchored within the ground with steel cables drawn therebetween under high tension. Such cable barrier systems offer high rupture strength, yet are more flexible to help prevent vehicle rebound, and are easier to install and repair when required.
In one known system, a socketed foundation with a concrete footing is installed for each line post along a roadway. A removable line post is then inserted within each socket and a steel cable is strung under tension therebetween. While effective, installing this system is complicated and time consuming. For each line post installed, significant time and labor is required to dig the footing hole, mix and pour concrete for the footing, and properly position and set the socket within the concrete to cure; this is all done on site. Each socketed foundation must then cure before the steel cabling system can be strung, thus requiring a separate operation. Moreover, most Department of Transportation (DOT) regulations now require the removal of all “spoils” caused by auguring the holes for the cement anchors, which adds additional time, cost and traffic disruption to the installation process. As is evident, multiple trips to the installation site result in increased installation time and consequent traffic diversion/stoppage. Importantly, it also significantly increases the potential for accident and injury to vehicles on the roadway, as well as the roadway workers installing such systems.
Other cabling systems utilizing pre-cast socketed concrete footings are also available, but such systems are less desirable in that they require larger holes to be dug for installation of the pre-cast footings, create more potential spoilage, and are less stable due to greater soil disruption. For proper installation, significant and time consuming packing of the soil around the pre-cast footing is required to stabilize each line post before stringing the cabling system. Still other cable barrier systems are presently available which utilize direct-driven line posts or sockets. While such systems are typically easier and less time consuming to install, again their anchoring systems are generally less stable and more prone to damage upon impact by a vehicle.
Upon such an impact by a vehicle, not only is damage typically caused to the vehicle and possibly the vehicle's passengers, but oftentimes the cable barrier system itself undergoes significant damage. In most cases, the cabling systems become damaged and the line posts are oftentimes bent severely beyond repair, thus requiring replacement. More significantly, however, is the fact that oftentimes the sockets that are fixed within the concrete footings are badly damaged and incapable of receiving another line post, or the concrete footing itself has been shifted out of proper alignment. In such cases, the entire footing must be removed and replaced because the damaged socket/concrete footing are fixed together as an integral unit. Such replacement causes a further significant disruption of the surrounding soil, thereby reducing the stability of the unit under repair. Obviously, such required frequent repairs are tedious, time consuming and expensive. More time is spent diverting and disrupting traffic flow, and the potential for accident and injury to others also increases.